Shock-resistant metal-walled discharge device



Sept. 19, 1950 H. N. PRICE SHOCK-RESISTANT METAL-WALLED DISCHARGE DEVICE Filed Dec. 22, 1949 Z I m:

Inventor: Harvey N Price,

His Attorn ey.

Patented Sept. 19, 1950 SHOCK-RESISTANT METAL-WALLED DISCHARGE DEVICE Harvey N. Price, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application December 22, 1949, Serial No. 134,509

2 Claims.

My invention relates to large discharge devices of the type having a metal casing and has particular reference to improvements in electrode seals for such devices.

When metallic envelopes or casings are used for discharge devices, as is commonly done in mercury pool discharge devices, insulating seals are required between the electrode terminals and the metal casing to maintain the envelope vacuum-tight. In installations where such discharge devices are subject to shock and severe vibration the seals are susceptible to cracking, especially when relatively massive electrodes are supported from the envelope by the seals. While there are various dielectric materials having suflicient mechanical strength and toughness for insulatingly supporting heavy discharge device electrodes, these materials are usually not fully suitable for use in a vacuum seal. It is also desirable, from the manufacturing standpoint to employ vacuum seals of conventional materials and at the same time provide sufficient mechanical support for the device electrodes necessary in installations where severe shock and vibration are encountered.

It is an object of my invention to provide a heavy duty electric discharge device for operation under severe conditions of vibration and shock.

It is a further object of my invention to provide improved arrangements for insulatingly and sealingly supporting a discharge device electrode from a conductive supporting Wall.

According to a feature of my invention, I employ in a metal wall electric discharge device, such as the large mercury pool type, a resilient electrode seal for insulating the cathode or anode from the metal envelope portion together with external insulating means for insulatingly supporting from the envelope the larger portion of the load imposed by the electrode mass, the additional support being outside the evacuated portion of the casing.

The features which I desire to protect herein are pointed out with particularity in the appended claims. The invention itself, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the drawing in which the single figure shows an electric discharge device embodying my invention.

Referring now to the drawing, I have shown my invention applied to a gaseous electric discharge device employing a pool type cathode l, which may be a suitable conducting liquid such as mercury, and a cathode make-alive electrode 2 consisting of a body of resistance material such boron carbide having its tip portion submerged in the mercury. A cooperating cylindrical anode 3, which may be suitably formed of graphite, is spaced a distance above the cathode pool I and may have one or more control grids surrounding it, such as illustrated in the drawing by the grid basket 4 surrounding the anode and insulatingly spaced from it. interposed between the lower face of the grid basket and the surface of the cathode pool, is a generally circular splash bafile 5. Such an electrode arrangement is typical of those employed for large power rectifiers, which, because of the relative massiveness of the electrodes, require special considerations in devising mechanically adequate electrode seals.

The above mentioned discharge device elements are housed in a generally cylindrical inner metal casing or tank 6 having one end insulatingly sealed to the anode 3 and the other end insulatingly Sealed to the cathode to form the envelope for the discharge device, together with sealing arrangements for auxiliary electrodes such as the make-alive electrode 2 and grid 4. The discharge device casing is completed by an outer generally cylindrical casing I surrounding the inner casing 6 and spaced from it. As deslribed in a following paragraph the ends of the outer casing I extend beyond corresponding ends of the inner casing 6 to help form an additional support for the cathode and anode assemblies. Spaced metallic closure rings 8 and 9 are provided between the inner and vouter casing 6 and l to enclose the space between the casings in order to permit circulation of water or other coolant, and pipe fittings ID or other suitable coupling arrangements are provided on the outer casing l to facilitate attachment of water lines. External mounting flanges H are welded or otherwise secured to the outer casing I.

For conductively supporting the anode, an anode support stem I 2, which may be suitably made of steel tubing, is shown with its lower end fixed to the upper end of the anode 3. The upper end of the support stem l2 extends through the top of the discharge device casing and is provided with an outwardly projecting metallic flange member I3. A. terminal for circuit connection is provided by a flexible copper cable I4 terminated at its extremity by a steel sleeve l5 which is welded to the upper end of the flange member l3. To insulatingly seal the anode assembly comprising anode 4 and its supporting stem 8 to the edge of the central aperture in an annular end plate 16 hermetically sealed to the inner cylindrical casing 6, an insulating cylinder I! of glass or other suitable gas-impervious material concentric with the anode stem is employed. A first metallic sleeve 18 is hermetically fastened between the flange l3 and the upper end of the glass cylinder I1, and a second sleeve [9 issi'milarly fastened between the end plate [6 and the lower end of cylinder l1. As shown in the drawing, the outer ends of sleeve members I8 and I9 are preferably bent over on themselves to provide a measure of flexibility in order that the anode seal may absorb a portion of the shock or vibration encountered.

Since the anode assembly is relatively massive and the insulating seal would be likely to break if required to absorb all the vibration and shock encountered, external insulating support members which may take the form of a plurality of insulated stud assemblies 20 positioned around top of the casing are provided. Each of the insulating assemblies 20 shown in the drawing comprises a bushing 2| of a strong and durable insulating material, such as a composition of mica and glass. The top and bottom ends of each bushing are internally threaded to hold firmly upper and lower studs 22 and 23. The lower stud members 23 are secured, preferably by threaded engagement, to a metallic flange 24 which is welded or otherwise firmly secured to the upper end of the outer casing I. A reinforced clamping disk 25, suitably made of steel, is bolted at its center to the anode flange memher 9 and at its periphery to the upper insulated studs 22 so as to support the anode insulatingly and carry the greater part of the stress which would be otherwise imposed on the seal.

As shown in the drawing, the cathode l is also insulated from the casing by an arrangement similar to that employed for the anode. A metallic bucket assembly 26 containing the cathode pool I is insulatingly sealed to the lower end of the inner casing by means of a pair of flexible metal sleeves 2i and 28, connected respectively to the lower end of the casing 6 and the periphery of the cathode bucket 26, and a cylinder 29 of glass or other dielectric impervious to gas into which the other end portions of sleeves 21 and 28- are sealed. An external insulating support for the cathode which may be suitably made of a durable and strong insulating material, such as hard rubber, is provided by an annular insulating member 30 having its outer periphery secured to the lower end of the outer casing l. The lower end of the cathode bucket 26 is supported from inner portion of the annular member 39 near its central aperture. An outlet for the flexible copper cable 3| which is connected to the cathode bucket to serve as a means for conducting current therefrom is provided by the central aperture in the insulating member 3|.

With the anode and cathode each insulated from the casing, the casing may be maintained at the mid-potential of the cathode and anode or at any potential relationship as desired. Insulation of the cathode is particularly desirable when a holding anode is employed in order to prevent the continuous are from wandering from the cathode to the inner casing 6. Both the cathode and anode need not be insulated from the casing in all installations, but in any case at least one of the main electrode seals would still be mechanically supported in a discharge device embodying my invention.

An auxiliary electrode seal is employed for sealing the control grid conductive lead through the upper end of the casing to an external terminal. Thus the grid basket 4, which is suitably supported by a tubular conductive support 32, may be suitably connected to an external terminal 33 by means of a suitable auxiliary seal 34. Part of the grid load support is preferably carried by one or more insulating bushings 35 supporting the grid support stem and secured to the inner surface of flange [6 closing the upper portion of inner casing 6. A similar auxiliary electrode seal 36 and support bushings 3'! are employed to insulate and support the make-alive electrode 2 from the inner casing 6.

While the present invention has been described by reference to a particular embodiment thereof, it will be understood that numerous modifications may be made by those skilled in the art without actually departing from the invention. I, therefore, aim in the appended claims to cover all such equivalent variations as come within the true spirit and scope of the foregoing disclosure.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. An electric discharge device of the single anode gaseous arc discharge type having as main electrodes a pool type cathode and an anode spaced from each other, a double walled metallic casing of generally cylindrical shape surrounding said cathode and anode and the space between them, said casing providing a passage between the walls thereof for a cooling fluid, the inner wall of said casing comprising an envelope for said anode and cathode. an insulating vitreous seal between one end of said inner wall and one of said main electrodes, and an insulating support connected between the corresponding end of the outer Wall of said casing and said one of said main electrodes, said corresponding end of said outer wall extending beyond said one end of said inner wall. said insulating support being arranged to support the greater part of the load imposed upon said insulating seal by said one of said main electrodes.

2. An electron discharge device or" the single anode gaseous arc discharge type comprising a double walled metallic casing of generally cylindrical shape having an inner and an outer wall fastened together and providing a passage between them for a cooling fluid, the ends of said outer wall extending beyond the corresponding ends of said inner wall, an anode of generally cylindrical shape positioned near one end of said inner wall, a first insulating vitreous seal between said end of said inner wall and said anode, a first insulating support connected between said anode and the end of said outer wall adjacent said anode, said insulating support being arranged to support the greater part of the load imposed on said support and said seal by said anode, a pool type cathode positioned near the other end of said inner wall, a second insulating vitreous seal connected between said other end of said inner wall and said cathode, and a second insulating support connected between the other end of said outer wall and said cathode, said insulating support being arranged to support the greater partof the load imposed upon said second seal and said second insulating support by said cathode.

HARVEY N. PRICE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,683,156 Brown Sept. 4, 1928 2,451,938 Garbuny et al Oct. 19, 1948 

